'06 EC300 fork damping adjustment
 

Manual describes the compression and rebound damping as turning the same dial on the top of the fork, with no mention as to what that screw is in the very center of the dial.

Can someone clarify how/where compression and how/where rebound damping is adjusted?

I already suspect I'll need lighter springs...

Firstly let us know what forks you have. Open chamber is comp at bottom and rebound at the top. Closed cartridge is the other way round with possibly some preload adjustability at the toP as well.
I do not know what the fork options were for the 06 but there will be others on here who will be able to give more info

Marzocchi forks.

Yes manual is wrong
There in one on the bottom not two on the top.
Rebound at the top I think